1. Field of the Invention
The present invention relates to a damper absorbing a torsional vibration of a rotating shaft, and more particularly to that provided with a trigger plate for detecting a rotation angle of the rotating shaft.
2. Description of the Conventional Art
In a damper absorbing a torsional vibration of a crank shaft of an automotive engine, there has been conventionally a structure provided with a trigger plate (a sensor plate) for detecting a crank angle of a crank shaft, for example, as disclosed in patent document 1.
Patent Document 1: Japanese Unexamined Patent Publication No. 11-281312
The trigger plate described in the patent document 1 is manufactured by a punching press from a magnetic material metal plate, and is structured such that a desired number of detected projections are formed at a predetermined pitch in a circumferential direction along an outer peripheral edge. On the other hand, a magnetic sensor (a crank angle sensor) is arranged at one position in the circumferential direction at an outer peripheral side of the trigger plate in a non-rotating state, and is structured such as to detect a crank angle for triggering an engine ignition apparatus and a fuel injection apparatus, by reading passage of the detected projections rotating together with the crank shaft.
However, in accordance with the prior art mentioned above, since the trigger plate is constituted by a substantially different member from the constituting parts of the damper, an increase of the number of parts of the damper is caused.